1. Field of the Invention
The present invention relates to a memory call origination system, and more particularly, to a memory call origination system associated with unattended recording and recording during communication available with a multi channel access (MCA) transmitter/receiver.
2. Description of the Related Art
A conventional wire message telephone is disclosed in, for example, Japanese Laid-Open Patent No. 314246/1992 (JP-A-04-314246). When a call comes in through the wire while the message telephone is in an unattended record mode, i.e., answer mode, an automatic answer section off-hooks and sends an answer message automatically. The answer message urges the calling person to send a speech message and a telephone number of the calling person. In order to send the telephone number, the caller dials his number, which is then transmitted over a speech channel as a dual tone multi-frequency (DTMF) signal. The speech message received from the calling person is stored into a speech recording section. The DTMF signal is converted to numerical data and stored into a dial recording section.
The user of the message telephone may then play back the recorded message. After the speech message stored in the speech recording section is played back, a reproducing section supplies a control signal for identification to the dial recording section. In response, the dial recording section originates a call automatically on the basis of the identified telephone number, by sending the telephone number in the form of a DTMF signal over a control channel.
As seen from the above description, in the conventional message telephone having a memory call origination system, a calling party may leave a speech message to be recorded by the called telephone system. The caller may also send its telephone number by dialing the number on the telephone set. The keyed telephone number is sent in the form of a DTMF signal over the speech channel. The DTMF signal is decoded and saved as numerical data by the receiving station.
Accordingly, in the system of the prior art, a caller number must be manually keyed in order for it to be received and saved by the receiving station. Moreover, since the number is transmitted as a DTMF signal over the speech channel, reliability is degraded when it is sent via a radio channel due to, for example, changes in electric field intensity and interference. In addition, in the system of the prior art, reception and storage of the calling number can be performed only during operation in answering mode.
Therefore, it is usually impossible to record the caller number during a conversation, and the conventional message telephone cannot be used to automatically originate a call to the caller number after the conversation has ended.